The present disclosure relates generally to communication networks, and more particularly, to providing differentiated services for unicast and multicast frames in Layer 2 (L2) topologies.
In conventional L2 networks, frames in a particular VLAN (Virtual Local Area Network) obtain service based on trees set up by Spanning Tree Protocol (STP) or its variants (e.g., RSTP (Rapid Spanning Tree Protocol), MSTP (Multiple Spanning Tree Protocol)). STP and related protocols are distance-vector protocols, therefore, frames are routed along links in the network that belong to the tree. L2 frames cannot be sent along Equal Cost Multipaths (ECMPs), since a requirement of STP is to ensure that the trees remain loop-free.
Multicast in these conventional networks is serviced using snooping mechanisms such as IGMP (Internet Group Management Protocol) snooping and MLD (Multicast Listener Discovery) snooping, which learn the location of hosts interested in a specific multicast group or multicast group and source Layer 2/Layer 3 address along the spanning tree and forward traffic accordingly. These STP based trees are not able to provide multipath services for multicast frames within a given STP instance.
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